Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
  • B21K1/00—Making machine elements
  • B21K1/02—Making machine elements balls, rolls, or rollers, e.g. for bearings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C11/00—Pivots; Pivotal connections
  • F16C11/04—Pivotal connections
  • F16C11/06—Ball-joints; Other joints having more than one degree of angular freedom, i.e. universal joints
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
  • B21K1/00—Making machine elements
  • B21K1/76—Making machine elements elements not mentioned in one of the preceding groups
  • B21K1/762—Coupling members for conveying mechanical motion, e.g. universal joints
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D7/00—Modifying the physical properties of iron or steel by deformation
  • C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C11/00—Pivots; Pivotal connections
  • F16C11/04—Pivotal connections
  • F16C11/06—Ball-joints; Other joints having more than one degree of angular freedom, i.e. universal joints
  • F16C11/0604—Construction of the male part
  • F16C11/0609—Construction of the male part made from two or more parts
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C23/00—Bearings for exclusively rotary movement adjustable for aligning or positioning
  • F16C23/02—Sliding-contact bearings
  • F16C23/04—Sliding-contact bearings self-adjusting
  • F16C23/043—Sliding-contact bearings self-adjusting with spherical surfaces, e.g. spherical plain bearings
  • F16C23/045—Sliding-contact bearings self-adjusting with spherical surfaces, e.g. spherical plain bearings for radial load mainly, e.g. radial spherical plain bearings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C2204/00—Metallic materials; Alloys
  • F16C2204/60—Ferrous alloys, e.g. steel alloys
  • F16C2204/62—Low carbon steel, i.e. carbon content below 0.4 wt%
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C2204/00—Metallic materials; Alloys
  • F16C2204/60—Ferrous alloys, e.g. steel alloys
  • F16C2204/74—Ferrous alloys, e.g. steel alloys with manganese as the next major constituent
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C2220/00—Shaping
  • F16C2220/40—Shaping by deformation without removing material
  • F16C2220/48—Shaping by deformation without removing material by extrusion, e.g. of metallic profiles
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49636—Process for making bearing or component thereof
  • Y10T29/49643—Rotary bearing
  • Y10T29/49647—Plain bearing
  • Y10T29/49648—Self-adjusting or self-aligning, including ball and socket type, bearing and component making
  • Y10T29/49664—Ball making

Definitions

• the invention relates to a method for producing balls or ball segments, in particular for ball joints, according to claim 1.
• the invention further relates to a ball element for two-part ball pins according to the preamble of claim 7.
• Two-part ball pins usually comprise a pin element and a separate ball perforated to receive the pin element. It is known here to produce balls for two-part ball pins, more precisely, ball elements such as perforated balls or ball segments by cold extrusion. In the prior art, for the production of the balls for two-part ball pins, tempering steel is usually used. After cold extrusion of the balls, the balls are first tempered. In connection with the nerging process, the balls are quenched by pouring the balls from the nerging furnace into the quenching medium in the hot or soft state.
• tempering steel has to be used for this.
• This quenched and tempered steel is, however, more expensive than other steels, which among other things is related to the fact that the quenched and tempered steel has to be drawn in a drawing shop to achieve the desired material structure and annealed on spherical cementite (GKZ).
• the balls made from tempering steel must of course be subjected to the corresponding tempering process after the cold pressing, so that the balls made from the tempering steel achieve the desired, intended hardness values and strength properties of the tempering steel.
• all of this is complex and therefore leads to high manufacturing costs for the balls.
• the balls should in particular be simple and inexpensive to manufacture.
• the problem of the occurrence of the impact points on the ball surface is to be overcome and the need to subsequently eliminate the impact points is eliminated.
• the high material and surface quality of the balls achieved with the known methods and the desired high strength of the balls should also be achieved or maintained.
• a rod section or wire section is produced from a semifinished product in a first method step.
• a semi-finished product which consists of micro-alloyed carbon-manganese steel.
• any carbon-manganese steel with microalloying elements that has been hot-rolled after melting and has a fine-grained ferritic-pearlitic structure is suitable in principle.
• the section is then pickled, in particular in order to remove oxidic coatings and to obtain a metallically clean surface of the section for the subsequent operations.
• the rod section or wire section is then shaped by cold extrusion in such a way that the desired spherical shape is produced.
• the spherical surface is ground to the intended dimension and shape.
• the method according to the invention is extremely advantageous in several respects.
• a micro-alloyed carbon-manganese steel is used to produce the balls.
• the micro-alloyed carbon-manganese steel in particular does not have to be tempered, but, as has been shown, achieves excellent strength and hardness by means of the cold deformation which takes place in the process step of cold extrusion of the ball from the rod or wire section.
• this also means that the balls can already be dimensioned considerably closer to the final dimensions during cold extrusion, since, as in the prior art, the considerable material removal during grinding of the balls, which is there to eliminate the impact points, no longer has to be taken into account was necessary.
• the semi-finished product used is more fully utilized, which already saves material costs.
• the time required for subsequent grinding is considerably reduced, since significantly less material has to be removed.
• the wear of the grinding tools and the amount of grinding sludge are significantly reduced, which also saves further costs and is environmentally friendly of the manufacturing process.
• the balls which are cold-pressed from microalloyed carbon-manganese steel, have even a considerably higher hardness than the tempered balls known from the prior art after the pressing, due to the cold working and due to the described special properties of the microalloyed steel.
• this higher hardness improves the grindability of the balls and shortens the necessary grinding time.
• this higher hardness improves the grindability of the balls and shortens the necessary grinding time.
• the sections are subjected to a drawing process in a further method step after the pickling, or it is carried out after pickling, annealing and drawing the sections on spherical cementite (GKZ treatment).
• GKZ treatment spherical cementite
• the wire or rod sections are phosphated and / or coated with a dry lubricant before the drawing or before the GKZ treatment.
• a dry lubricant layer is arranged on the carrier layer, which has sufficient pressure resistance during cold extrusion and thus prevents metallic contact between the workpiece and the tool.
• graphite, molybdenum disulfide, special soaps or waxes can be used as pressure-resistant solid lubricants.
• the balls are nitrocarburized in a further process step.
• Nitrocarburizing leads to improvements in corrosion resistance and wear resistance, especially in the case of surface adhesion between the ball and the bearing shell. Furthermore, a nitrocarburized surface has a reduced coefficient of friction. The reason for this is the so-called connection layer that is produced on the surface of the sphere during nitrocarburizing and has a thickness of only a few hundredths of a millimeter. Nitrocarburizing is also a comparatively environmentally friendly process and is an advantageous alternative to galvanically deposited layers. Nitrocarburization is preferably carried out in a salt bath.
• the balls are after after grinding or after nitrocarburizing, polished or re-ground in a further process step and then polished. This further increases the corrosion resistance and wear resistance of the ball surface, and the coefficient of friction is further reduced.
• the carbon-manganese steel has a microalloying element for accelerating the nitrogen uptake during nitriding or nitrocarburizing.
• the microalloying element is particularly preferably vanadium.
• vanadium in particular as a microalloying element accelerates the nitrogen uptake during nitriding.
• higher hardness values and greater hardening depths of the connecting layer can be achieved with unchanged nitriding times, which also further improves the corrosion behavior.
• the same advantageous properties of the connecting layer as with tempered steel can be achieved with shorter process or nitriding times.
• the salt bath process time can be reduced by 33% from 90 minutes to 60 minutes in this way.
• the invention also relates to a ball element, in particular for two-part ball pins.
• a two-part ball pin is composed essentially of a pin element and a perforated ball element in a manner known per se.
• the spherical element is distinguished by the fact that it consists of tempering-free carbon-manganese steel with micro-alloy elements.
• the micro-alloyed carbon-manganese steel does not require a tempering process, but has excellent strength and hardness due to the cold forming Extrusion on.
• the remuneration necessary for the production of the balls according to the prior art can be omitted, as a result of which the corresponding outlay and the associated costs are also eliminated.
• the problem of undesired striking points on the spherical surfaces is solved, since the problematic pouring of the hot or soft spheres from the tempering furnace into the quenching medium is eliminated without replacement.
• the microalloyed carbon-manganese steel is drawn, GKZ-treated or coated, in particular phosphated.
• the spherical element is nitrocarburized. This improves corrosion resistance and wear resistance as well as the friction behavior of the ball element, in particular with regard to the adhesion between ball and bearing shell that occurs in ball joints due to the low angular velocities.
• the ball element is ground and / or polished, whereby balls are obtained for particularly high-quality, durable and low-friction ball joints.
• the microalloying elements comprise vanadium.
• FIG. 1 shows the micrograph of the microstructure of a tempering steel for balls according to the prior art
• FIG. 2 shows the structure of a microalloyed carbon-manganese steel for balls according to the present invention in a representation corresponding to FIG. 1
• 3 shows a logarithmic plot of the cumulative fracture probability P against the tensile strength ⁇ in MPa according to Weibull
• 4 shows in a linear bar representation a comparison of the strengths of balls produced according to the invention with tempered balls according to the prior art
• 5 shows the properties of the connecting layer produced by nitrocarburization in balls produced according to the invention in comparison with tempered balls according to the prior art
• FIG. 6 shows a ball produced according to the invention for a two-part ball pin in two different views.
• FIG. 1 shows the greatly enlarged micrograph of the ferritic-pearlitic structure of a tempering steel for balls according to the prior art. Specifically, this is the structure of a hot-rolled standard tempering steel with the designation 41Cr4.
• FIG. 2 shows the micrograph of the likewise ferritic-pearlitic microstructure of a micro-alloyed carbon-manganese steel for balls according to the present invention in the same magnification as for the micrograph of the heat-treatable steel according to FIG. 1.
• micro-alloyed steel with the designation 35V1 or C-Mn-V, which is also hot-rolled during manufacture.
• This steel has the following alloying elements (all information in
• the structure of the micro-alloyed steel according to FIG. 2 is much finer than that of the conventional tempering steel according to FIG. 1.
• the fine structure of the micro-alloyed steel according to FIG. 2 leads in particular to particularly good cold formability of the micro-alloyed steel, which advantageously accommodates the production of the balls according to the invention by cold pressing.
• the representation is the cumulative fracture probability P in the form of a Weibull distribution, plotted logarithmically on the vertical axis, against the tensile strength ⁇ in MPa plotted on the right axis.
• the tensile strength was calculated in accordance with DLN 50150 from measured hardness values, the hardness values being measured at different points on the balls.
• the diamond-shaped measuring points designated with the letter A in the legend relate to the balls made of microalloyed carbon-manganese steel produced by cold pressing according to the invention.
• the square measuring points designated with the letter B in the legend in FIG. 3 relate to balls made from a tempered steel according to the prior art. Specifically, this is a common tempering steel with the designation 38MnB5.
• the triangular measuring points designated by the letter C in the legend in FIG. 3 in turn relate to the spheres according to the invention made of microalloyed carbon-manganese steel, the triangular measuring points relating to the spheres according to the invention after nitrocarburizing. It can be seen in FIG.
• Balls for ball joints without impact points are particularly advantageous, since this enables particularly smooth-running, long-life and low-wear ball joints, which show a particularly low tendency to stick-slip effects when the ball moves in the bearing shell.
• the greater hardness of the balls of microalloyed carbon-manganese steel according to the invention is also advantageous in that it also improves the corrosion resistance and the friction behavior when the balls are used in ball joints.
• FIG. 3 also shows the strength of the spheres according to the invention made of microalloyed carbon-manganese steel, applied in the form of triangular measuring points, after the spheres according to the invention have been subjected to nitrocarburization. From the intersection of the imaginary Weibull straight line (the straight line defined by a group of measuring points in each case) with the y-axis at zero, it can be seen that the spheres according to the invention made of microalloyed carbon-manganese steel still have strength values even after nitrocarburization (triangular measuring points ), which are as high as those of the balls made of tempered steel (square measuring points).
• FIG. 4 again shows the tensile strength, determined according to DLN 50150, from the hardness of various balls according to the invention made of a further microalloyed carbon-manganese steel with the designation 10MnSi7 (dotted vertical bars on the right in each case), and the tensile strength of the wires from which the respective balls are made (left hatched vertical bars).
• the representation of FIG. 4 again contains the strength values of a heat-treatable steel according to the prior art (horizontal bar) for comparison. The percentages on the right axis indicate the extent to which the wire from which the balls were pressed was pulled off before pressing. The wire was removed after hot rolling and before the balls were pressed.
• the unrefined balls made from the microalloyed carbon-manganese steel (right dotted beams in each case) consistently have a higher strength than the balls made from the tempered steel (horizontal bar), and to a large extent independently of the degree of wire pulling and the resulting connected strength of the wire or starting material (left-hand hatched bars).
• 5 shows the hardness profile according to the invention of a compensation-free, Microalloyed carbon-manganese steel (35V1) produced ball after nitrocarburization, the hardness measurements being plotted against the depth below the ball surface.
• letter C again stands for the measured values of the carbon-manganese steel (triangular measuring points).
• the corresponding hardness measured values of a ball made of conventional tempering steel according to the prior art are also plotted in the diagram according to FIG. 5, see again letter B in the legend in FIG. 5 (square measuring points).
• the balls according to the invention made of microalloyed carbon-manganese steel have a higher hardness than corresponding balls made of tempered steel according to the prior art (square measuring points) even after nitrocarburizing.
• the higher hardness is, as already explained above, i.a. advantageous for the particularly good wear resistance of the balls according to the invention and for a time and cost-saving, improved machinability of the balls during grinding.
• FIG. 5 also shows the target values for the hardness on the surface or at 0.2 mm depth that are structurally predetermined for balls for ball joints, see the two horizontal bars in the diagram according to FIG. 5. It can be seen that the connecting layer of the balls according to the invention (triangular measuring points) complies with or even exceeds the required hardness target values.
• FIG. 6 shows a ball made according to the invention from tempering-free, micro-alloyed carbon-manganese steel for a two-part ball pin, which is perforated to receive the pin element, in two different views. It can be seen that the balls can be produced using the method according to the invention without problems, in particular without cracks and with a perfect surface quality.
• the invention thus makes an important contribution to the particularly economical production of high-quality balls, in particular for ball joints, wheel suspensions, stabilizers and for comparable purposes.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Heat Treatment Of Articles (AREA)
• Heat Treatment Of Steel (AREA)
• Pivots And Pivotal Connections (AREA)
• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
• Forging (AREA)

Applications Claiming Priority (2)

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• 2004
  • 2004-05-04 DE DE102004022248A patent/DE102004022248B4/de not_active Expired - Lifetime
• 2005
  • 2005-05-02 WO PCT/DE2005/000823 patent/WO2005106263A1/de active Application Filing
  • 2005-05-02 MX MXPA06012713A patent/MXPA06012713A/es unknown
  • 2005-05-02 EP EP05747383A patent/EP1743103A1/de not_active Withdrawn
  • 2005-05-02 US US11/568,640 patent/US20070211972A1/en not_active Abandoned
  • 2005-05-02 KR KR1020067023368A patent/KR101157685B1/ko active IP Right Grant
  • 2005-05-02 BR BRPI0510575-7A patent/BRPI0510575B1/pt not_active IP Right Cessation
  • 2005-05-02 CN CN2005800142590A patent/CN1950619B/zh active Active
  • 2005-05-02 JP JP2007511851A patent/JP2007538203A/ja active Pending

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